Acute thromboembolic events, venous and arterial thrombosis, pulmonary embolism, intracardiac thrombosis and systemic embolism are difficult to manage. Current medical therapy for the occlusion itself commonly involves anticoagulation. The current medical approach is designed to stop the underlying process and to rely on normal physiologic mechanisms for restoring blood flow and limiting the extent of vascular obstruction or destruction of tissue. Thrombolysis or thrombolytic therapy would be of considerable interest as a means for lysing the offending thromboembolism. By using both anticoagulation and thrombolytic therapy, medical practice would have the means to dissolve thromboemboli quickly and prevent their recurrence. Recently, several approaches to thrombolytic therapy have been under investigation, one being through the systemic infusion of activators of the naturally occurring fibrinolytic enzyme system. One such agent which has undergone extensive study is urokinase. Urokinase is a thrombolytic agent active through the conversion of plasminogen to plasmin. Plasminogen is the naturally occurring plasma precursor which, in the presence of an activator, is converted to plasmin, the proteolytic enzyme capable of hydrolyzing fibrin. Urokinase is a complex protein of unknown structure which is found in human urine in trace amounts. It is a potent blood clot lysing agent and when injected in amounts far greater than those which exist naturally in the blood will promote the dissolution of blood clots. It was first described in 1951 after which processes for the isolation and purification of uorkinase from human urine were developed. Methods for the isolation and purification of urokinase are described in many publications, such as U.S. Pat. Nos. 2,983,647; 3,256,158; 3,477,910 to 3,477,913 and 3,544,427. However, the logistics of urine collection and processing makes this source of urokinase impractical, four million CTA (Committee on Thrombolytic Agents) units of urokinase requiring the processing of about 1,500 liters of urine. Fibrinolytic activity in cultures of human kidney cells was later demonstrated, and it was found that this activity was immunologically indistinguishable from urinary urokinase. Even using tissue culture processes, high production costs result, and, consequently, other methods for the preparation of urokinase are desirable.